The present invention is directed to an elastomeric mount of the type used to support and isolate an engine from a vehicle chassis. More particularly the present invention is directed to a mount which has four preferably inclined elastomeric elements, each of which is simultaneously preloaded in compression and shear.
In applications involving on- and off-highway equipment, elastomeric mounts must be rugged to take the pounding from traversing unimproved roads. In addition, these mounts should be designed to avoid total disconnect of the power train from the support in the event of elastomer failure (i.e., they are safetied). Finally, the provision of snubbing in all three orthogonal directions protects the power train, improves subjective ride quality and reduces unwanted chatter caused by metal-to-metal contact.
The mount of the present invention provides a safetied design that uses four preferably inclined elastomeric elements which are formed by spaced laterally extending compartments, and the elastomeric elements preferably being mechanically locked or bonded to four outwardly facing faces of an inner member and to the four opposing inwardly facing faces of an outer member. Even should the elastomeric elements all fail, the inner member will be retained within the outer member. In several of the described embodiments, either of the inner or outer member are bifurcated into separate elements and, in preassembled condition, the elements are spaced such that opposed mating surfaces of the upper and lower elements are non-engaging. In its final assembled position, the two mating surfaces are brought together, preferably into engaging contact resulting in each of the elastomeric components experiencing preloading in both the compressive and shear directions. In Another embodiment, the inner and outer members are each one element, and the elastomeric components are bonded between parallel plates and preloaded between the opposing faces of the members. This preload results in superior wear life of the elastomeric elements. Snubbing is preferably provided in each of the two vertical and the fore/aft (not lateral) directions to eliminate metal-to-metal contact and resulting mechanical chatter.
In one embodiment, the opposing surfaces of the inner and outer members are designed to be non-planar in order to increase the stiffness of the mount in a lateral direction. In other embodiments, auxiliary lateral elements are used. This increase in spring rate raises the natural frequency of the mounting system out of an undesirable frequency range defined by the vehicle structure. In yet other embodiments, the bifurcated elements of the outer member interengage to maintain the mount in its assembled condition prior to installation. In still another embodiment, chevron-shaped elastic assemblies are each formed in an X-configuration as separate elastomeric elements bonded between parallel edge plates for maximizing mold capacity, and for reducing manufacturing cost. Precompression of the elastic assemblies between the inner and outer members serves to increase load-carrying capacity. To prevent the elastic assemblies in the X-configuration due to repetitive loading from being displaced and completely dislodged from between the opposing inner and outer members of the engine mounting, another embodiment is provided in which retaining plates on opposite faces of the elastomeric elements are formed with turned-out ends which grip respective adjacent edges of the inner and outer members. An alternative configuration of the outer member is also provided whereby the loading on each bolt attaching the outer member to a support structure is more in tension than in bending.
Various other features, advantages and characteristics of the present invention will become apparent after a reading of the following specification.